I agree with Dabeeeenster on this one, I just spent the last 20 mins playing with wave and although I had a big spurt of "Wow, this is really cool, real time comms", I was also faced with a usability question of "What is this" and more worryingly, "What can I do now".
It's not obvious what you can do with the system easily. I spent about 10 mins trying to tag up a google map whilst other people did the same, the result being a map dragging fight and trying to type in a description before someone deletes the pin.
In summary... er... It might be useful for small internal groups of people you know, but it's going to need some marketing and training.